Method for making coils for armatures of electrical machines or the like

ABSTRACT

Armature coils for use in electrical machines are produced on a revolving pattern of polygonal outline. A continuous length of wire having a current-conducting core surrounded by an insulating sheath is fed under tension to the peripheral surface of the revolving pattern. A set of pushers cooperate with the pattern to move successively formed convolutions axially of the pattern. A cutting device which severs the wire between selected convolutions to form a succession of coils comprises a finger which orbits about the pattern and a reciprocating device which moves the finger axially at predetermined intervals so that the finger loops the wire between selected convolutions and moves the thus engaged part of the wire against a counterknife which is adjacent to the periphery of the pattern. A removing device strips the insulation off those portions of the wire which are to be severed by the cutting device so that the coils are formed with blank terminals.

[ Teb.22,1972

United States Patent Boke et al.

140/9 2 2 X ...140/92.2 X 29/605 X Lancaster [72] Inventors: Reinhard Boke; Alfred Schmid; Heinz p E c i 11M Wilkes all of Hlldeshelm, Germany Assistant Examiner-Carl E. Hall [731 Assignee: Robert Bosch Gmblil, Stuttgart, Germany Am'"ey-Mchaels-Smker ABSTRACT May 27, 1969 [22] Filed:

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y of e pattern. A cutting device which severs the wire between selected convolutions to form a succession of coils com a finger which orbits about the paattem and a rec of wire having a currentconducting core surrounded by an in sulating sheath is fed under tension to the peripheral surface of the revolving pattern. A set of pushers cooperate with the pattern to move successively formed convolutions axiall th prises iprocating device which moves the finger axially at predetermined intervals so that the finger loops the wire between selected convolutions and moves the thus engaged part of the wire against a counterknife which is adjacent to the periphery of the pattern. A removing device strips the insulation off those portions of the wire which are to be severed by the cutting device so that the coils are formed with blank terminals.

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....242/7.13 X .......29/605 X Forsberg...........................140/922 X 3 Claims, 9 Drawing Figures 2,122,894 7/1938 Sager 2,666,168 1/1954 Lorant 3,010,667 11/1961 PMHEDFEW m2 SHEET 1 BF 3 HNVENTORS Reinhard BOKE Alfmcl SC HMID Hmnz y WILME their ATTORN EY PMENTEDFEB22 I972 sum 2 UP 3 g v w W 2 4 INVENTORS Reinhard BOKE Alfred SCHMID Heinz WILKE their ATFTQR N EY Pmmmnaaw 1972 396% 326 INVENIORS Reinhard BOKE Alfred SCHMID Heinz WILKE their TOR N EY METHOD FOR MAKING COILS FOR ARMATUIIES OF ELECTRICAL MACHINES OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for making coils which can be utilized in armatures of electrical machines, for example, in dynamos or in starters for automotive vehicles.

Certain presently known apparatus for the production of armature coils comprise a stationary pattern and an arm which orbits about the pattern and winds the wire therearound. It is also known to mount several equidistant patterns radially on a turret and to index the turret at intervals so as to place successive patterns into requisite position with reference to the orbiting arm. The arm coils the wire around successive patterns to form thereon coils which are integrally connected to each other. Each pattern which carries a freshly formed coil is moved into registry with a cutting device which serves the wire between the coils on two adjoining patterns, and the thus separated coils are thereupon stripped off the corresponding patterns before the patterns return into registry withthe orbiting arm. A drawback of such apparatus is that they comprise a large number of parts and that only one coil is formed at a time despite the fact that the apparatus comprises a substantial number of patterns, Furthermore, the distance between adjoining patterns on the indexible turret cannot be reduced at will so that the terminals of coils are longer than necessary. Consequently, the terminals must be trimmed in a separate operation which contributes to the initial cost of coils. Also, the parts of the device for guiding and feeding the wire to the orbiting arm must be designed, finished and operated with a high degree of precision because the tension of wire must be maintained within a narrow range. It was found that the just described conventional apparatus are not suited for the production of any desired type of coils; as a rule, such apparatus are useful only in the production ofcoils from relatively thin wire which is employed in coils of armatures for dynamos or the like.

It is also known to provide an apparatus for the production of coils with a rotary pattern which receives wire from a stationary guide. The just described apparatus are not suited for the production of coils which are used in armatures of electric starters for automatic vehicles or the like; the wire which is processed in such apparatus is of rectangular cross-sectional outline and the convolutions are formed on top of each other, not adjacent to each other in the axial direction of the coil as is required in armatures of starters and analogous electrical machines.

SUMMARY OF THE INVENTION An object of our invention is to provide a method of forming coils for use in armatures of starters or other types of elec trical machines according to which a continuous length of wire can be converted into a succession of coils without any waste and in such a way that the terminals of each of a series of successively formed coils are of identical length which is best suited for further processing ofcoils.

Another object of the invention is to provide a method according to which each of a series of successively produced coils is ofidentical dimensions and/or configuration and which can be employed with equal advantage for the production of coils having any desired number of convolutions and consist ing of any desired type of wire which is needed in the armature of an electrical machine or the like.

A further object of the invention is to provide a novel coilmaking apparatus which is of simple design, which occupies little room, which can be used for the production of coils on a large scale, and which can be operated automatically by resorting to a relatively simple programming system.

An additional object of the invention is to provide an ap paratus which is capable of automatically providing each successive coil with one or more bare terminals to facilitate the connection of such coil into the electric circuit of an electrical machine, for example, into the circuit of a starter for automotive vehicles or the like.

Still another object of the invention is to provide the apparatus with novel wire tensioning, coiling, severing and stripping devices.

The method of our invention is utilized for the production of coils on a revolving pattern, particularly for the production of armature coils for use in electrical machines by employing a wire having a current-conducting ductile core surrounded by an insulating sheath and by resorting to a pattern whose peripheral surface is of polygonal outline. The method comprises the steps of feeding to the revolving pattern a continuous length of wire so that the wire is convoluted around the peripheral surface of the pattern, preferably under at least some tension to insure that the convolutions assume the outline of the peripheral surface, moving successively formed convolutions axially toward and beyond one axial end of the pattern, and severing the wire between selected convolutions on the revolving pattern (i.e., prior to moving the convolutions beyond the one axial end) to subdivide the convoluted wire into a succession of coils. The step of feeding preferably includes maintaining the wire under tension upstream of the revolving pattern, and the severing step comprises severing the wire between each nth and mth convolution wherein m equals n+1 and n is a whole number including 1.

The method preferably further comprises the step of exposing longitudinally spaced portions of the core prior to severing and thereupon severing the core across such exposed portions so that each coil exhibits one or two bare terminals. The severing step preferably includes forming the wire with looped portions between the selected convolutions whereby such looped portions extend radially beyond the peripheral surface of the pattern, and severing the looped portions across the middle so that one-half of each looped portion constitutes one terminal of a preceding coil and the other half of each looped portion constitutes one terminal ofthe next-following coil.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specified embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a fragmentary perspective view of an apparatus which is designed for the production of coils each of which comprises two convolutions and is utilized in the armature of a starter for automotive vehicles, certain parts of the apparatus being shown in partial section;

FIG. 2 is an elevational view of the apparatus as seen in the direction of arrow A in FIG. 1, with certain parts shown in vertical section;

FIG. 3 is a sectional view as seen in the direction of arrows from the line IIIIII of FIG. 2;

FIG. 4 is a sectional view as seen in the direction of arrows from the line IV-IV of FIG. 2;

FIG. 5 is a fragmentary perspective view of a knife in the insulation removing device of the apparatus shown in FIGS. I and 2;

FIG. 6 is a sectional view as seen in the direction of arrows from the line Vl-VI of FIG. 2;

FIG. 7 is a similar sectional view but showing the pattern in a different angular position;

FIG. 3 is a section as seen in the direction of arrows from the line VIII-VIII of FIG. 2, the pattern being shown in still another angular position; and

FIG. 9 is an elevational view of a finished coil.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus which is shown in FIGS. 1 and 2 comprises a rotary pattern having an outline (see FIGS. 6 to 8) which is identical with that of the outline of a finished armature coil 90 (FIG. 9). The pattern 10 is fixedly secured to a drive shaft 11 which is joumaled in the frame F of the apparatus and is rotated by a motor or another suitable prime mover, not shown. A sidewall or cheek 12 is adjacent to one axial end of the pattern 10 and extends radially beyond the polygonal peripheral surface 13 of the pattern. This cheek 12 rotates with the pattern 10 and serves as a support for four displacing members or pushers 14 which are movable in parallelism with the axis of the drive shaft 11 and are biased in a direction to the right, as viewed in FIG. 2, by helical springs 15. Each pusher 14 has a roller follower 14a which tracks the face of an arcuate control cam 16 provided on a platen or holder 17 secured to or forming part of the frame F. The center of curvature of the cam 16 is located on the axis of the drive shaft 11. The exact configuration of the face of this cam is shown in FIG. 3. It will be noted that the cam extends along an arc of more than 180. The face of the cam 16 slopes toward the pattern 10, as seen in a clockwise direction, up to a ridge 18 shown in FIG. 3 and thereupon slopes sharply toward the adjoining side face of the holder 17. The maximum height of the cam 16 is in the region of the ridge 18 and equals the diameter of the wire48 which is being converted into a succession ofarmature coils 90. The front faces 14b of the pushers 14 are immediately adjacent to the peripheral surface 13 of the pattern 10 so that such front faces can shift freshly formed convolutions 148 (FIG. 2) in the axial direction of the shaft 11 and away from the cheek 12 when the roller followers 14a track the rising section of the cam face, i.e., when such followers travel in a clockwise direction, as viewed in FIG. 3 to move toward the ridge 18. When the roller followers 14a track the side face of the holder 17, the front faces 14b of the corresponding pushers 14 are flush with the left-hand face 46 of the cheeklZ (see FIG. 2).

The apparatus further comprises a second shaft 20 which is coaxial with the drive shaft 11 and is rotatable in bearings 21, 22 provided in the frame F. The shaft 20 is reciprocable axially toward and away from the shaft 11. The aforementioned prime mover rotates the shaft 20 at the exact speed of the shaft 11. The shaft 20 is a crankshaft; it carries a radially extending crank arm 23 for an orbiting loop forming and cutting member or finger 24 which is outwardly adjacent to the peripheral surface 13 of the pattern 10 and has an axially parallel cutting edge 25. This cutting edge 25 cooperates with a second cutting member or counterknife 26 which is an idler roller mounted in the frame F on a shaft 26a which is parallel to the shafts II and 20. The crank arm 23 defines with the adjoining side face of the pattern 10 a compartment or space 27 (FIG. 2) which is provided for the purpose of permitting evacuation of successively formed armature coils 90 by a gripper or another suitable transfer member, not shown, operated by a suitable mechanism to repeatedly enter and leave the space 27 in order to engage and remove successively produced coils which are pushed off the peripheral surface 13 at the left-hand axial end of the pattern 10.

The shaft 20 is fixed to a disk 30 which carries a bearing member 31 for a roller follower 32 whose axis extends radially of the shaft 20. The follower 32 tracks the face 34 ofa second cam 35 which is a spur gear and is rotatably mounted on the shaft 20. The cam 35 is rotated by a drive including a pinion 36. This pinion 36 rotates the cam 35 in the direction of rotation of the shaft 20 but at half the speed of this shaft. A helical spring 37 surrounds the shaft 20 and reacts against the bearing 22 to bias the disk 30 and shaft 20 in a direction away from the bearing 22 so that the roller follower 32 bears against the face 34 of the cam 35. The latter is thereby biased against the bearing 21.

The face 34 of the cam 35 is shown in FIG. 4. It comprises a section 41 which is located in a plane making a right angle with the axis of the shaft 20 so that the axial position of the disk 30 remains unchanged when the roller follower 32 tracks the section 41. When the roller follower 32 tracks the section 41, the shaft 20 assumes an axial position in which the cutting edge 25 of the finger 24 is in the plane of the counterknife 26. This is shown in FIG. 2 wherein the surface 42 of the finger 24 is coplanar with the end face 43 of the counterknife 26. The section 41 is followed by a section 44 (as seen in the clockwise direction of the cam face 34 shown in FIG. 4) which slopes away from the disk 30 and merges into a further section 45 located in a plane which is parallel to the plane of the section 41. When the roller follower 32 tracks the section 45, the surface 42 of the finger 24 is coplanar with the left-hand end face 46 of the cheek 12. The shortest distance between the planes of the faces 43, 46 exceeds the diameter of the wire 48. The cam face 34 further comprises a fourth section 47 which constitutes a gradually sloping transition from the section 45 to the section 41. During a full revolution of the disk 30 with reference to the cam 35, the finger 24 moves axially from the illustrated position to a foremost position in which its surface 42 moves into the plane of the face 46 on the cheek l2 and back to illustrated position. Since the cam 35 rotates at half the speed of the disk 30 and shaft 20, the finger 24 moves axially toward the cheek 12 once during two successive revolutions of the shafts 11, 20 to thereby engage and loop and sever the oncoming wire 48 in a manner to be described hereinafter.

The wire 48 is paid out by a suitable reel, not shown, and is coiled once around a tensioning roller or sheave 50 which forms part of the wire feeding means and is freely rotatable on a shaft 51. Such coiling insures that the wire 48 cannot slip with reference to the peripheral surface of the roller 50. This roller is biased axially by a helical spring 52 which reacts against a flange 53 on the shaft 51 and urges the roller against a brake disk 54 which is affixed to the shaft 51. Thus, a certain torque is necessary to rotate the roller 50; this insures that the wire 48 is maintained under tension in the region between the roller 50 and pattern 10. The positioning of the roller 50 with reference to the'pattern 10 is such that successive increments of the wire 48 reach the peripheral surface 13 of the pattern in a predetermined plane which is immediately adjacent to the face 46 of the cheek 12.

The wire 48 comprises a metallic current-conducting ductile core and a sheath of insulating material. Such insulating material is removed from the wire 48 at predetermined intervals by a removing device 60 which is installed between the tensioning roller 50 and the pattern 10. The device 60 comprises two knives 61, 62 having substantially semicircular concave stripping edges 63 (see FIG. 5), which together define an opening through which the wire 48 is normally free to advance in response to rotation of the pattern 10. The knives 61, 62 are mounted on carriers or slides 64, 65 which are reciprocable radially of the wire 48 in a support of the frame F. A fluidoperated working cylinder 66 accommodates two reciprocable pistons whose piston rods are coupled to two-armed levers 67, 68. These levers are respectively coupled to slides 64, 65. The piston rods can move the knives 61, 62 to positions in which the face 69 (FIG. 5) of the knife abuts against the adjoining face of the knife 61. This reduces the size of the opening between the stripping edges 63 to such an extent that the opening merely permits passage of the metallic core of the wire 48.

The means for actuating the cylinder 66 comprises a valve 72 which is connected with the cylinder by conduits 70, 71. The valve 72 is a solenoid valve and its operation is controlled by an electric switch 73 in synchronism with rotation of the shaft 20. The movable contact of the switch 73 is connected with a roller follower 74 which tracks a cam 76 provided with a lobe 75. The cam 76 is fixed to the cam 35. When the lobe 75 engages and displaces the roller follower 74, the switch 73 causes the valve 72 to open and to admit a pressure medium into the cylinder 66 so that the face 69 of the knife 62 abuts against the face of the knife 61 and the stripping edges 63 of the knives cooperate to remove a length of insulation on the traveling wire 48. Removal of insulation is terminated as soon as the lobe 75 moves beyond the roller follower 74. The pistons in the cylinder 66 are biased away from each other, for example, by suitable springs, so that the knives 61, 62 move apart as soon as the valve 72 is free to close.

The operation: 7

In the first step, the operator winds the leading end of the wire 48 once around the peripheral surface 13 of the pattern 10. The illustrated pattern has a polygonal peripheral surface 13 with six corners which effect such deformation of the leading end that the wire 48 is thereupon drawn lengthwise in response to starting of the motor which drives the shafts 11 and 20. The spring 52 biases the roller 50 against the brake disk 54 so that the wire 48 is tensioned in the region upstream of the pattern 10. Successive increments of the wire 48 engage the peripheral surface 13 in a plane which is immediately adjacent to the left-hand face 46 of the check 12 and such increments are convoluted around the peripheral surface 13. The pushers 14 travel about the axis of the shaft 11 and are caused by cam 16 to move in parallelism with the axis of the shaft 11 so that they provide room in the plane which is immediately adjacent to the face 46 of the check 12, i.e., successive increments of the wire 48 are free to engage the peripheral surface 13 in immediate proximity of the cheek 12 while the pattern rotates with the drive shaft 11. The latter is rotated continuously so that the wire 48 is drawn at a constant rate and forms a succession of convolutions 148.

The shaft 20 rotates with the drive shaft 11 and causes the finger 24 to orbit about the peripheral surface 13 of the pat tern 10. The speed of the finger 24 is the same as the speed of the shaft 11. Not later than during each second revolution of the pattern 10, the cam 35 shifts the shaft 20 to move the finger 24 in the axial direction of the shaft 11 (see FIG. 6) whereby the finger 24 engages a bare portion 80 of the core in the wire 48 (see FIG. 7) and causes the adjoining portion 81, 82 of the wire to form the sides ofa loop which resembles an isosceles triangle after the pattern 11) turns through about 90 beyond the position shown in FIG. 6. The loop including the portions 81, 82 extends radially outwardly beyond the outline of the previously formed convolution 148. The portions 81, 82 are integral with each other until the finger 24 reaches the position shown in FIG. 8 in which its cutting edge 25 cooperates with the counterknife 26 to sever the wire 48 midway across the bare portion 80. During movement of the finger 24 from the position of FIG. 7 to that of FIG. 8, the spring 37 causes the finger to return to the axial position shown in FIG. 2 to move its cutting edge 25 into the plane of the counterknife 26. The same procedure is repeated during each second revolution of the shaft 11 so that the wire 48 is ultimately converted into a succession of coils 90 one ofwhich is shown in FIG. 9.

As stated before, the cam is rotated by the pinion 36 at half the speed of the pattern 10. The cam 76 and its lobe 75 share angular movements of the cam 35. The lobe 75 actuates the switch 73 once during each revolution of the cam 76 and the switch 73 then effects opening of the valve 72 which operates the removing device 60. The knives 61, 62 removes portions of insulation at regularly recurring intervals to provide the wire 48 with the aforementioned bare portions 81) (see FIG. 8) where the core of the wire is fully exposed. The distance between successive bare portions 80' equals the length of a coil 90. The operation of the cylinder 66 is synchronized with rotational speed of the shaft 11 in such a way that the cutting edge 25 severs the wire 48 exactly mid way across successive bare portions 80 (see FIG. 8) so that the finished coil 90 is formed with two blank or bare currentconducting terminals 80" (FIG. 9). successively finished coils 90 are shifted axially of the shaft 11 by pushers 14 and slide along the peripheral surface 13 of the pattern 10. Each coil 90 comprises two convolutions and, therefore, each portion 81 is offset from the corresponding portion 82 of the same coil by a distance corresponding to the diameter of the wire 48 (as seen in the axial direction of drive shaft 11). Otherwise stated, each portion 81 or 82 ofa preceding coil 98 is spaced from the portion 81 or 82 of the next-following coil '90 by two diameters of the wire 48.

The pushers 14 shift freshly formed coils 90 along the peripheral surface 13 and away from the cheek 12 whereby the foremost coil slides offthe pattern 16 and enters the space 27 where it is engaged by the aforementioned gripper. This gripper transports the coils 90 to a further processing station where the portions 81, 82 are deformed to assume a predetermined shape. The portions 81, 82 need not be trimmed because the cutting edge 25 of the finger 24 cooperates with the counterknife 26 in such a way that each of the portions 81, 82 has an optimum length when the freshly formed coil 98 is separated from the remainder of the wire 48.

An important advantage of the improved apparatus is that the pattern 10 can rotate continuously and need not be indexed between successive positions. Also, the bare portions of the wire 48 are severed while the convolutions 148 flanking such portions are still supported by the peripheral surface of the pattern. The improved apparatus is simpler and more compact than presently known apparatus, and its output exceeds considerably the output of such conventional apparatus. The aforementioned arm which is used in apparatus with indexible patterns can be dispensed with; this renders it possible to utilize our apparatus for making coils from relatively thick and strong wire. Since the finger 24 can be orbited in close proximity of the peripheral surface 13, the length of terminals 88 on finished coils 96 can be readily selected in such a way that they need not be trimmed subsequent to removal of coils from the pattern. Thus, the length of terminals 80" can be so selected that they are best suited for connection to a collector in a starter for automotive vehicles or the like. Since the removing device 60 operates in synchronism with the device (including the cam 35) which shifts the finger 24 axially to engage the wire 48 between selected convolutions on the pattern 10, utilization of the removing device 60 does not cause any delays or reduction in the speed of our apparatus.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is:

1. A method for making armature coils for electrical machines on a revolving pattern comprising the steps of feeding to the pattern a continuous length of wire which consists at least in part of ductile material; convoluting the wire around the pattern while maintaining the wire upstream of the revolving pattern under tension so that convolutions on the pattern follow closely the outline of its peripheral surface while moving each successively formed convolution axially of the revolving pattern thereby creating space on the pattern for each subsequent convolution; forming the wire between selected con volutions with looped portions extending radially of and being disengaged from the revolving pattern; and severing the convoluted wire on the revolving pattern at selected looped portions to subdivide the wire into a succession of coils.

2. A method as defined in claim 1, wherein said severing step comprises severing the wire between each nth and mth convolution and wherein n is a whole number including one and m=n+l.

3. A method as defined in claim 1, wherein wire having a core of current-conducting material surrounded by an insulating sheath is used, further comprising the step of exposing longitudinally spaced portions of the core upstream of the revolving pattern, said severing step comprising severing the exposed portions of the core so that the ends of each coil exhibit bare portions of the core. 

1. A method for making armature coils for electrical machines on a revolving pattern comprising the steps of feeding to the pattern a continuous length of wire which consists at least in part of ductile material; convoluting the wire around the pattern while maintaining the wire upstream of the revolving pattern under tension so that convolutions on the pattern follow closely the outline of its peripheral surface while moving each successively formed convolution axially of the revolving pattern thereby creating space on the pattern for each subsequent convolution; forming the wire between selected convolutions with looped portions extending radially of and being disengaged from the revolving pattern; and severing the convoluted wire on the revolving pattern at selected looped portions to subdivide the wire into a succession of coils.
 2. A method as defined in claim 1, wherein said severing step comprises severing the wire between each nth and mth convolution and wherein n is a whole number including one and m n+
 1. 3. A method as defined in claim 1, wherein wire having a core of current-conducting material surrounded by an insulating sheath is used, further comprising the step of exposing longitudinally spaced portions of the core upstream of the revolving pattern, said severing step comprising severing the exposed portions of the core so that the ends of each coil exhibit bare portions of the core. 